Gestational diabetes is a function of complex metabolic adjustments in maternal, placental and fetal compartments. The studies proposed here are designed to examine relationships among maternal metabolism and endocrine status and fetal growth and development. A key tissue involved in this interaction is the placenta. It is proposed that the placenta acts as a buffer to the fetus by adjusting its metabolism to insure a constant flux of essential nutrients for fetal growth. The mechanism(s) by which the placenta alters carbohydrate lipid and amino acid metabolism is not completely understood. Concisely the experiments in Series I, "Placental Tissue Metabolism and Lipid Transport Mechanisms," are designed to: a) determine the role of fatty acid binding protein in placental tissue uptake and utilization of fatty acids; b) identify the predominant pathways of amino acid metabolism in both fetal and maternal placentas; c) to characterize the pattern of fetal and maternal tissue carbohydrate metabolism during various stages of gestation. In the second series of experiments, "Nutritional Aspects of Gestational Diabetes," the mechanism(s) by which diet influences gestational diabetes will be investigated. It is proposed that diet plays a key role in altering maternal and fetal carbohydrate status and that the placenta acts to buffer metabolic and endocrine changes induced by the maternal diet. The last series, "Endocrine Aspects of Gestational Diabetes," examines specifically the endocrine responsiveness of the fetal and maternal placentas and provides the background for isolation of factors which precipitate the diabetic state in some pregnancies.